<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <select name="" id="set1">
        <option value="">请选择省份：</option>
        <option value="" id="yi">北京</option>
        <option value="" id="er">河北</option>
        <option value="">河南</option>
        <option value="">江苏</option>
        <option value="">浙江</option>
        <option value="">四川</option>
        <option value="">吉林</option>
        <option value="">辽宁</option>
        <option value="">江西</option>
        <option value="">云南</option>
        <option value="">青海</option>
        <option value="">甘肃</option>
        <option value="">安徽</option>
    </select>
    <select name="" id="set2">
        <option value="">请选择市：</option>
    </select>

    <!-- <select name="" id="province"></select>
    <select name="" id="city">
        <option value="">请选择市</option>
    </select> -->

    <script>

        var arr1 = ['北京1', '北京2', '北京3']
        var arr2 = ['河北1', '河北2', '河北3']

        var sum = document.getElementById('set1').value
        var num = docuemnt.getElementById('set2').value
        var yi1 = document.getElementById('yi')
        sum = arr1
        num = arr2
        if (sum == yi1) {

        }




        // var arr = [
        //     {
        //         name:'北京',
        //         shild:[
        //             {shi:'北京1'},
        //             {shi:'北京2'},
        //             {shi:'北京3'},
        //         ]
        //     },
        //     {
        //         name:'河南',
        //         shild:[
        //             {shi:'洛阳'},
        //             {shi:'郑州'},
        //             {shi:'濮阳'},
        //         ]
        //     },
        //     {
        //         name:'河北',
        //         shild:[
        //             {shi:'张家口'},
        //             {shi:'石家庄'},
        //             {shi:'石家庄1'},
        //         ]
        //     }
        // ]




        // var obj1 = document.getElementById('set1').option
        // var obj2 = document.getElementById('set2')

        // var arr1 = ['北京1','北京2','北京3','北京4','北京5','北京6','北京7','北京8','北京9']
        // var arr2 = ['河北1','河北2','河北3','河北4','河北5','河北6','河北7','河北8','河北9']
        // // var lis = ''
        // if(set1 == '北京'){
        //     set2 += arr1
        // }else if(set1  == '河北'){
        //     set2 += arr2
        // }

    </script>

</body>

</html>